1. Field of the Invention
The present invention relates to a mobile telecommunication station, and more particularly, to a mobile telecommunication station which is connected to a mobile telecommunication network and is provided with mobile telecommunication services from the network.
At the present time, the number of subscribers of mobile telephones, handheld telephones, and other telecommunications equipment is rapidly increasing. The systems are accordingly being strained to their limits in terms of channel capacity. To deal with this, the industry has come out with a plan to change the former full rate (11.2 kilobits/sec) communication speed using vector sum excited linear prediction (VSELP) to a half rate communication speed using PSI-code excited linear prediction (CELP) by voice signal compression technology. Quick completion of such a half rate system at the base station side is now being awaited.
2. Description of the Related Art
As will be explained in detail later by using the drawings, a base station specifies a full rate/half rate radio channel in accordance with the transmission rate of a mobile telecommunication unit. Responding to this, the mobile telecommunication unit performs the communication at the full rate or half rate. Accordingly, carriers are working to improve the functions of the base stations and, at the same time, sell half rate units so as to secure the required channel capacity.
In this type of communication system, however, it is necessary to fully confirm the air interface match between the base station and the mobile station in advance by using the actual network. At the very least, it is necessary to perform full confirmation tests for the basic functions of the cellular telephone set, that is, the call origination and termination processing, hand-off processing between cells, transmission power control, speech continuing processing, etc., by using an actual cellular network while taking into account the wave propagation characteristics.
For this reason, the half rate unit must be sold after being fully checked for operation when the system on the base station side is completed. Accordingly, it is not possible in practice to secure enough of a channel capacity to keep up with the rapid increase of the subscribers.
On the other hand, if the half rate unit were to be sold to the consumer without conducting a full confirmation test, not only might unexpected damage be given to the exchange, switching network, consumer, etc., but also it would be necessary to notify the subscribers by direct mails or the like and ask them to go to the service shop so as to change the functions (firmware or the like) of the once sold mobile telecommunication units. This would place a heavy burden on both of the consumer and the carrier performing the maintenance.